1. Field of the Invention
The present invention relates generally to hydraulic couplings used in undersea drilling and production applications and seals used in those couplings. More particularly, the invention involves an undersea hydraulic coupling with an extended probe on the male member and a valve spring configured to secure the valve in a closed position to prevent leakage of hydraulic fluid or seawater at high pressure. One or more seals engage the extended probe.
2. Description of Related Art
Subsea hydraulic couplings are old in the art. The couplings generally consist of a male member and a female member, with soft seals positioned within the female member to seal the junction between the male and the female members. The female member is generally a cylindrical body with a relatively large diameter longitudinal bore at one end and a relatively small diameter longitudinal bore at the other. The small bore facilitates connections to hydraulic lines, while the large bore contains soft seals and receives the male portion of the coupling. The male member includes a cylindrical portion, or probe, at one end having a diameter approximately equal to the diameter of the large bore of the female portion of the coupling. The male member also includes a connection at its other end to facilitate connection to hydraulic lines. When the cylindrical portion of the male member is inserted into the large bore of the female member, according to the various embodiments of the device, the soft seals, or O-rings, either abut the end or face of the male member or engage the cylindrical probe wall about its outer circumference. The hydraulic fluid is then free to flow through the female and male members of the coupling and seals prevent that flow from escaping about the joint and the coupling. A check or poppet valve may be installed in the female member and also in the male member. Each valve opens when the coupling is broken so as to prevent fluid from leaking out of the system of which the coupling is a part.
In U.S. Pat. No. 4,694,859 to Robert E. Smith, III, assigned to National Coupling Co., Inc. of Stafford, Tex., an undersea hydraulic coupling and metal seal is disclosed. This patent describes a reusable metal seal which engages the outer circumference of the probe when it is positioned within the female member bore. The metal seal is held in place by a retainer. When the male and female portions of the coupling are parted under pressure, the retainer prevents the metal seal from blowing out through the bore of the female member. The male and female members each have valve actuators extending from the poppet valves. When the valve actuators are engaged, each of the poppet valves is urged open and the poppet valve springs are compressed.
Other subsea hydraulic couplings include seals that engage the face of the male member or probe. For example, U.S. Pat. No. 4,637,470 relates to a coupling having a male member and female member with valves, and a face seal for sealing the junction between the members.
As subsea hydraulic systems are needed for drilling and production applications at increasing depths, the subsea pressure exerts greater forces against the valves in the coupling members. Typically, when the coupling members are disengaged, the male member remains at a subsea location while the female member is removed. The valve spring (typically having a diameter of less than one inch) in the male member may not be adequate to keep the poppet valve completely closed against the hydrostatic forces of sea water. If the valve opens slightly, seawater may enter the hydraulic lines or hydraulic fluid may escape from the system. In known coupling designs for subsea use, increasing the size (i.e., the diameter) of the valve spring would also require increasing the corresponding dimensions of the coupling member, or probe, where the valve spring is positioned. However, increasing the dimensions of the coupling member presents the problem of adequately sealing the coupling members together. Seals for use in undersea hydraulic couplings of the type described herein typically seal around the circumference or face of a probe having an outer diameter of approximately one inch. A seal or seals for engaging a probe having a diameter significantly larger than one inch will be subject to greater hydraulic forces that tend to increase the separation forces between the male and female members and make it more difficult to engage and disengage the coupling members. Therefore, a male coupling member is needed that will be configured to house a larger valve spring to assure that the poppet valve remains closed against the hydrostatic head of the sea, without increasing the dimensions of that portion of the male coupling member where the seal engages.